1. Field of Invention
The invention relates to an ink-jet recording apparatus, and more particularly, to an ink-jet recording apparatus that traps air bubbles developed in an ink-flow passage to absorb a kinetic pressure produced in the ink-flow passage using the air bubbles and efficiently discharges the trapped air bubbles, thereby maintaining excellent printing quality.
2. Description of Related Art
There has been an ink-jet recording apparatus of ink tube supply type that supplies ink to a recording head via a tube from an ink tank. The ink-jet recording apparatus includes a recording head for ejecting ink droplets onto a recording medium to perform recording, a carriage on which the recording head is mounted, an ink tank that stores the ink to be supplied to the recording head, and a tube that supplies the ink from the ink tank to the recording head.
According to the ink-jet recording apparatus of the ink tube supply type, it is unnecessary to mount the ink tank on the carriage. Therefore, the recording head can become compact and lightweight, so that recording operation can be performed by moving the carriage at high speed. Further, an amount of storage capacity of the ink tank, which is separately provided from the recording head, can be increased. Thus, a replacing period of the ink tank (an ink supply period) can be elongated.
The recording head has an ink nozzle for ejecting an ink droplet therefrom. In order to eject ink stably from the ink nozzle, a meniscus of ink is formed at an end of the ink nozzle, for example, by controlling a pressure for supplying ink to the ink nozzle to a negative pressure within a predetermined level. Therefore, the ink supply pressure is maintained at a predetermined pressure to form the same meniscus all the time.
However, the recording head is mounted on the carriage that reciprocates to perform recording onto the recording medium. Acceleration and deceleration of the carriage movement provide a large acceleration to the recording head and the tube connected with the recording head. The acceleration generates a kinetic pressure in the ink in the tube. The kinetic pressure is transmitted to the recording head and breaks the meniscus formed at the ink nozzle. Accordingly, an ink droplet can not be stably ejected, so that recording quality is affected by the kinetic pressure.
The invention provides an ink-jet recording apparatus that can maintain excellent recording quality, by which air bubbles developed in an ink passage are stored in an air trap unit and a kinetic pressure generated in the ink passage is absorbed by the air bubbles.
According to one aspect of the invention, an ink-jet recording apparatus includes a recording head, an ink supply source, an ink passage, an air trap chamber, a purge device, a partition, and a filter. The recording head has at least one ink nozzle and performs recording onto a recording medium by ejecting ink from the ink nozzle. The ink supply source stores ink to be supplied to the recording head. The ink passage is connected to the ink supply source to supply ink from the ink supply source to the recording head. The air trap chamber has an upper wall, a bottom wall, side walls, and is connected to the ink passage to store air generated in the ink passage. The purge device generates an ink-flow that passes from the air trap chamber to the recording head and is faster than an ink-flow generated at the recording operation. The partition divides inside of the air trap chamber into a first chamber and a second chamber. the first chamber is connected with the ink supply source. Further the partition is provided in the air trap chamber so as to provide a first connecting portion that communicates the first chamber with the second chamber above the partition. The filter divides a lower portion of the air trap chamber into the first chamber at an ink supply source side and a third chamber at a recording head side. The third chamber connects the first chamber and a lower end of the second chamber with the recording head. The filter allows the ink to flow from the first chamber to the third chamber through the filter and offers resistance to the high-speed ink-flow generated by the purge device. In the inkjet recording apparatus, air is separated from the ink entered into the air trap chamber and is trapped at an upper portion of the first chamber, and the air trapped in the first chamber is discharged from the nozzles by the purge device that generates the high-speed ink-flow that passes the first, second and third chambers in order.